feat(mission-control): give the list handler its own review task

"Let Claude handle it" now creates one ClaudeDo task per run to host the
ConPTY session (Idle/IsManual, never queued) instead of an untracked
ad-hoc tile, so the run has a real title, diff, and review outcome.
Since the handler merges its own changes straight into the list's
working dir, the task never gets a WorktreeEntity; its review range
lives as new HandlerBaseCommit/HandlerHeadCommit columns on TaskEntity
instead, reusing the existing commit-range diff machinery and keeping
it out of the worktrees overview entirely.

tests/ClaudeDo.Worker.Tests/UiVm/TasksIslandViewModelPlanningTests.cs

@@ -77,6 +77,9 @@ sealed class FakeWorkerClient : IWorkerClient
         => Task.FromResult(new LaunchSpec(".", "claude", Array.Empty<string>(), new Dictionary<string, string>()));
     public Task<LaunchSpec> GetMergeHelperLaunchSpecAsync(IReadOnlyList<string> taskIds, string listId, CancellationToken ct = default)
         => Task.FromResult(new LaunchSpec(".", "claude", Array.Empty<string>(), new Dictionary<string, string>()));
+    public Task<string> CreateMergeHelperTaskAsync(
+        IReadOnlyList<string> taskIds, string listId, string title, string descriptionHeader, CancellationToken ct = default)
+        => Task.FromResult(Guid.NewGuid().ToString());
     public Task<LaunchSpec> GetAdHocLaunchSpecAsync(string directory, CancellationToken ct = default)
         => Task.FromResult(new LaunchSpec(directory, "claude", Array.Empty<string>(), new Dictionary<string, string>()));
     public int PlanningStartSpecCalls { get; private set; }